The present invention relates to manufacturing processes in a sheet fabrication environment and more particularly to a system and process therefor to sort and unload finished pieces in a flexible manufacturing system.
In a numerically controlled sheet fabrication center, to produce parts from sheet blanks, part programs or routine files are used. Ordinarily, these part programs are stored in data banks so that an operator can retrieve one or more for each production or batch run. If the part desired has never been produced before, a new part program, or routine file, has to be written by a programmer for effecting that particular part from a sheet blank.
Each part program is considered a file and includes geometrical and technological definitions of the to be cut part. Some of the technological definitions include tooling data (size and shape of the tool, angle and position of tool changer, etc.), the order of tooling operation (which tool operates first, second, etc.), and the working sequence of a tool (what operations the tool performs and in what sequencexe2x80x94also known as optimized tool path). Among technological definitions, an important one is the sorting address, which is the location where a finished part is placed by the system.
Production requirements in sheet fabrication centers are such that certain parts need to be produced within a given delivery time. To achieve this end, programmers are given a list of parts that are required so that they can write a xe2x80x9cnest programxe2x80x9d for producing those parts. Some of the parameters which are utilized in a nest program include the sheet blank sizes that are available and the required material thickness. The nest program will select from among the available sheet blanks the one with the size that is most suitable for operation. In particular, in a nest program, the required different parts are laid out in accordance with the dimension of the selected sheet blank in an optimal fashion to maximize material utilization. In other words, scraps from the sheet blank are to be minimized.
The nest programs are run in the system sequentially. As parts defined by each of the nest programs are produced, they are sorted and directed to sorting addresses pre-defined for them in the nest program. Nest programs can be generated automatically from given production requirement lists and existing program files or routines. One existing software for defining such nest program is the JETCAM from the Finn-Power company.
The sorting addresses refer to the different locations in the unloading area of the part sorting and unloading system to which finished parts are to be placed. When a sorting address becomes full or when the product run is completed, the parts have to be removed from the sorting and unloading system in order to make room for the next production run. The operation for the removal in most cases involves manual labor. However, in advanced flexible manufacturing systems, such removal of parts may be done automatically.
The sorting and unloading of finished parts to different sorting addresses ordinarily proceeds uneventfully. However, in practice, given the limited quantity of available sorting addresses and the very large or unlimited quantity of different parts, problems do occur. For example, a produced part may have a sufficiently large dimension to cover more than one conventional sorting address to thereby limit the number of available sorting addresses in the system. Alternatively, if the production run requires that a large quantity of differently dimensioned parts be produced, then there may not be sufficient sorting addresses.
Yet another problem that occurs is when parts from different nest programs in the same production run have been designated by the respective nest programs to have the same sorting address or overlapping addresses. In this instance, insofar as the controller has no way of arbitrating which part from which nest program should take precedence over a particular sorting address, oftentimes the production run is stopped to allow the programmer/operator to effect modifications to the nest programs to rearrange the sorting addresses so that all parts may be sorted properly. Needless to say, this stopping of the system during a production run leads to inefficiency, lost production time, increased production cost and delivery times, and additional reset work to rearrange the sorting addresses.
To overcome the above problems, the present invention system incorporates a xe2x80x9cdenesterxe2x80x9d approach in which, prior to a production run, all of the nest programs to be run during the production are reviewed and all data relevant to the to be cut pieces are retrieved. The relevant data may include, for example, the sizes and dimensions of all of the parts to be cut during the production run with each of the nest programs. The dimensions from the different parts are then resorted and assigned to respective sorting addresses. Parts that have the same dimensions are assigned the same sorting address so that those same parts are directed to a particular location at the unloading area of the sorting and unloading system.
Since all the parts to be cut during the production run are analyzedxe2x80x94at least with respect to the respective dimensions and the number of those parts to be cutxe2x80x94prior to the production run, as parts are cut during the production run, those parts are directed to the sorting and unloading system in a predetermined fashion such that each part is directed to a corresponding sorting address. Since like parts are directed to the same sorting address, no conflict would arise even when sheet blanks are cut into different dimensioned pieces in accordance with different nest programs. Thus, with all part sizes, quantity and quality information predetermined, layouts for the sorted parts, in terms of the unloading area to which the sorted pieces are to be placed, is optimized so that all of the available part sorting addresses in the system are utilized to maximum capacity. No sorting address is therefore xe2x80x9coverloadedxe2x80x9d or xe2x80x9cunder utilizedxe2x80x9d. Moreover, the production run will not be stopped on account of any potential xe2x80x9caddress flow alarmxe2x80x9d or xe2x80x9csorting address conflictxe2x80x9d in the middle of the production process. The setup time therefore decreases while production run efficiency increases. Furthermore, no intervention by the programmer/operator is required.
In the event that new nest programs are added during the production run, insofar as sorting addresses for the different dimensioned cut pieces have already been determined, the different pieces to be cut from each of the newly added nest programs can readily be routed to the appropriately predetermined sorting address. And a new sorting address is automatically calculated by the processor of the system for any of the to be cut pieces from any of the newly added nest programs which does not have a corresponding predetermined sorting address.
The calculation of any such new sorting address takes into consideration the unused space, if any, that is available at the being operated on unloading area. If no unused space is available at the being operated on unloading area, a new sorting address is created at a new unloading area. The being operated on unloading area is replaced by the new unloading area when the system begins to cut pieces from a work blank in accordance with the newly added nested program.
With the present invention system and method, a number of sorting and unloading systems can be utilized. Thus, different sorting addresses may be assigned to different systems. Some such exemplar sorting and unloading systems include a conveyor mechanism, a sorting device, a robot unloader mechanism, and a stacker mechanism.
An objective of the present invention is therefore to provide a system and method for ensuring a smooth production run in a sheet fabrication system.
It is yet another objective of the present invention to provide a system and method for ensuring optimal utilization of sorting addresses and therefore efficient unloading of cut pieces of different sizes and/or dimensions.
It is still another objective of the present invention to provide a system and method in which cut pieces of the same dimension are stacked in an unloading area of a pallet, storage bin, or cassette such that the available space of an unloading area is efficiently utilized.